Bias-selectable mid-/long-wave dual band infrared focal plane array based on Type-II InAs/GaSb superlattice

In this paper, a mid-Tong-wave dual-band detector which combined P pi MN structure and unipolar barrier was developed based on type-II InAs/GaSb superlattice. A relevant 320 x 256 focal plane array (FPA) was fabricated. Unipolar barrier and P pi MN structure in our dual band detector structure were used to suppress cross-talk and dark current, respectively. The two channels, with respective 50% cut-off wavelength at 4.5 mu m and 10 mu m were obtained. The peak quantum efficiency (QE) of mid wavelength infrared (MWIR) band and long wavelength infrared (LWIR) band are 53% at 3.2 mu m under no bias voltage and 40% at 6.4 mu m under bias voltage of -170 mV, respectively. And the dark current density under 0 and -170 mV of applied bias are 1.076 x 10(-5) A/cm(2) and 2.16 x 10(-4) A/cm(2). The specific detectivity of MWIR band and LWIR band are 2.15 x 10(12) cm.Hz(1/2)/W at 3.2 mu m and 2.31 x 10(10) cm.Hz(1/2)/W at 6.4 mu m, respectively, at 77 K. The specific detectivity of LWIR band maintains above 10(10) cm.Hz(1/2)/W at the wavelength range from 4.3 mu m to 10.2 mu m under -170 mV. The cross-talk, selectivity parameter at 3.0 mu m, about 0.14 was achieved under bias of -170 mV. Finally, the thermal images were taken by the fabricated FPA at 77 K. (C) 2017 Elsevier B.V. All rights reserved.